phenibut interaction question

I have been taking phenibut 2-3 time a week for about a year now. 4 weeks ago I was diagnosed with a deep vein blood clot in my calf and am now on a daily coumadin regimen. I have been on vicodin for about three weeks to treat the terrible pain in my leg, and would like to start taking the phenibut to help ease off the painkillers. Does anyone know of any interaction between coumadin and phenibut? Any help would be greatly appreciated.